If you are new to the Raspberry Pi you might want to start back to my earlier posts.

Got 3 things from Adafruit today:

1. Many more assorted M/M jumper wires (you really want lots of lengths and colors).
2. A DHT22 temperature/humidity sensor.
3. A POS-type motion sensor.

In a mere hour I have the DHT working. I'm getting better at this! However, there were some wrinkles to work out.

• The best info on how to use the Adafruit wiring plan and code was in French at http://www.manuel-esteban.com/lire-une-sonde-dht22-avec-un-raspberry-pi/ -- luckily I still remember enough francais from 60 years ago to get by.
• The sample program did the hard part of reading the DHT22, but it didn't suit me otherwise. More luck: that program was written in C Language. While at the old Bell Labs and Clemson U. I programmed mostly in C from 1972 to the late '90s. I simplified the program down to what I needed and fixed a small bug: the code as I found it returned success even when the DHT22 was read incorrectly. 

I still have the motion sensor to conquer. But who's worried.

I'm still working toward a vegetable farm automation system. While pawing through Raspi references I found--

   http://rayshobby.net/blog/?page_id=562#ospi

Ray (assuming it's a person, probably male) has developed an add-on interface board for the Raspi that can control an 8-station irrigation setup. It costs about $150, plus the Pi, plus the irrigation parts. For another $50 you get 8 more hose valve controls. There is even code for controlling every valve from the Internet. Or -- it can be operated from a Google calendar. 

Here's my messy setup du jour: